Q. No.Secondary productivity in an ecosystem can be defined as:
1.
The amount of chemical energy, typically expressed as carbon biomass, that primary producers create in a given length of time.
2.
The rate at which all the autotrophs in an ecosystem produce net useful chemical energy.
3.
The rate of formation of new organic matter by consumers.
4.
The amount of energy released by the action of detritivores and decomposers in an ecosystem.
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Suppose in an area, the energy present in total incident sunlight falling on primary producers is 10,00,000 J and about 10,000 J is converted by them into biomass. What percent of PAR have the primary producers been able to convert?
| 1. | 1 % | 2. | 2 % |
| 3. | 10 % | 4. | 20 % |
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In primary ecological succession in water, the pioneers are:
1. Mosses
2. Lichens
3. Phytoplankton
4. Free floating hydrophytes
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If we put a price tag on nature’s life-support services, about 50 % of the total cost will be accounted for by:
1. Recreation and nutrient cycling
2. Soil formation
3. Climate regulation
4. Habitat for wildlife
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Consider the given two statements:
| I: | Human burning of fossil fuels today is creating large contemporary imbalances in the carbon cycle. |
| II: | It has significantly increased the rate of release of carbon dioxide into the atmosphere. |
| 1. | Both I and II are correct and II explains I. |
| 2. | Both I and II are correct but II does not explain I. |
| 3. | I is correct but II is incorrect. |
| 4. | I is incorrect but II is correct. |
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On the land, almost all primary production is performed by:
| 1. | Phytoplanktons | 2. | Algae |
| 3. | Mosses and Liverworts | 4. | Vascular plants |
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The ecological pyramids that can never be inverted in a natural ecosystem include:
| I: | pyramid of numbers |
| II: | pyramid of energy in any ecosystem |
| III: | pyramid of biomass in the sea |
1. Only II
2. Only III
3. Only II and III
4. All can be inverted
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Energy flow and nutrient cycling are two important components of an ecosystem. What will be true comparison of the two?
| 1. | The amount of energy is much greater than the amount of nutrients |
| 2. | Organisms always need nutrients, but they don't always need energy |
| 3. | Nutrients are recycled, but energy is not |
| 4. | Organisms always need energy, but they don't always need nutrients |
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Primary succession takes a very long time when compared to secondary succession, primarily, because:
1. immigration of pioneer species takes time
2. soil formation is a very slow process
3. there is a low availability of ecological niches
4. environmental conditions are highly variable
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Consider the two statements:
| I: | Food chains rarely extend for more than 4 or 5 levels. |
| II: | Consumers at each level convert, on an average, only about 10% of the chemical energy in their food to their own organic tissue. |
1. Both I and II are correct and II explains I.
2. Both I and II are correct but II does not explain I.
3. Only I is correct.
4. Both I and II are incorrect.
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